Spatio-temporal dynamics of the vegetation and seed bank of beaver meadows in Riding Mountain National Park, Manitoba
Shaw, Michael P.
The seed banks of beaver ponds and meadows, and the vegetation of beaver meadows, were examined along the upper reaches of the Little Saskatchewan River in Riding Mountain National Park, Manitoba. A total of eleven beaver meadows (one 1 year old, four 6 year old, four 9 year old, a 21 year old and a 22 year old), and six beaver ponds, were examined. The soils of the 11 beaver meadows were also examined for differences in five soil factors: soil moisture, pH, organic matter, bulk density, and conductivity. The vegetation and soil data were examined using canonical correspondence analysis. The results indicated that the vegetation of beaver meadows does change with age and soil factors. The youngest meadows are characterized by high cover of annuals and short-lived perennial plant species. By the sixth year, the grass Calamagrostis canadensis and the sedge Carex atherodes come to dominate all sites. The oldest meadows are drier have the highest shrub densities. The seed banks of beaver meadows are dominated by annual and short-lived perennial plant species, and become less and less similar to the extant vegetation with increasing meadow age. The composition of the seed bank of full beaver ponds was significantly different from that of beaver meadows, and showed lower species richness. There is some evidence that the seed bank of each pond is somewhat unique, with a floristic trend from the most upstream to the most downstream sites. The pond seed banks were most similar to the vegetation of the one-year-old meadow.